Overview
EN ISO 1833-29:2020 specifies a quantitative chemical analysis method using sulfuric acid to determine the mass percentage of polyamide (after removal of non-fibrous matter) in textiles that are binary mixtures of polyamide with polypropylene/polyamide bicomponent. Adopted by CEN, this part of the ISO 1833 series is intended for laboratory and quality-control use where accurate, standardised content determination is required - notably in carpet and technical textile applications where bicomponent yarns are common.
Key Topics
- Scope: Applicable to mixtures of polyamide with polypropylene/polyamide bicomponent. The bicomponent typically contains 10 % to 25 % by mass of polyamide fibrils within a polypropylene matrix.
- Principle: Dissolve polyamide from a known dry mass of the specimen using 75 % (mass fraction) sulfuric acid; collect, wash, dry and weigh the remaining residue. The difference yields the polyamide/polypropylene bicomponent percentage.
- Reagents: Uses 75 % (approx. 73–77 % acceptable range) sulfuric acid, plus specified diluted sulfuric acid and diluted ammonia rinses as described in ISO 1833-29.
- Procedure summary: Add sulfuric acid (100 ml per gram of specimen), shake and stand periods at room temperature (three cycles including 30 min rests), filter through a weighed crucible, wash sequentially with diluted acid, water and diluted ammonia, rinse, dry and weigh the residue. Calculation follows ISO 1833-1 general instructions; the document specifies a correction factor d = 1.005 where required.
- Precision: On homogeneous mixtures, confidence limits are within ±1 percentage point at the 95 % confidence level.
Applications
- Quality control and composition verification for carpets and textile products containing polypropylene/polyamide bicomponent yarns.
- Laboratory testing for material declarations, procurement specifications and regulatory compliance.
- Comparative testing in research and development where accurate quantification of polyamide content is needed.
Practical benefits: a standardised, repeatable test method; compatibility with existing ISO 1833 test series procedures; clear precision parameters for interpreting results in QC workflows.
Related Standards
- ISO 1833-1 - General principles and calculation methods used across ISO 1833 parts.
- ISO 1833-7 - Method using formic acid for other polyamide mixtures (not suitable here because formic acid dissolves all polyamide components).
- ISO 1833-18 - Sulfuric acid based method used as reference for adapting operating conditions.
- ISO 2076 - Definitions for man-made fibre generic names (source for bicomponent definition).
This part of ISO 1833 is endorsed as EN ISO 1833-29:2020 by CEN and is intended as the harmonised test method for determination of polyamide in polyamide/ polypropylene-polyamide bicomponent textile mixtures.
